1. Field of the Invention
This invention is directed to a coating composition useful for providing a finish on a variety of substrates. In particular, this invention is directed to an organosilane composition useful for finishing automobiles and trucks.
2. State of the Art
It is well-known that consumers prefer automobiles and trucks with an exterior finish having an attractive aesthetic appearance including high gloss and excellent DOI (distinctness of image). While ever more aesthetically attractive finishes have been obtained, deterioration of the finish over time, whereby the exterior finish of an automobile or truck loses its luster or other aspects of its aesthetic appearance, is all the more noticeable. An increasingly observed cause of this deterioration is etching of the finish caused by exposure to environmental chemical attack. Chemicals that can cause etching of a finish include acid rain and chemical smog.
In order to protect and preserve the aesthetic qualities of the finish on a vehicle, it is generally known to provide a clear (unpigmented) topcoat over a colored (pigmented) basecoat, so that the basecoat remains unaffected even on prolonged exposure to the environment or weathering. It is also generally known that alkoxysilane polymers, due to strong siloxane bonding when cured, exhibit excellent chemical resistance. Exemplary of prior art literature disclosing silane polymers for coating are U.S. Pat. Nos. 5,244,696 and 5,223,495.
There is a continuing need for a commercially practical clearcoat finish having excellent appearance, including high gloss and DOI, that is also resistant to etching caused by chemical attack. To be commercially practical, such a clearcoat must not be prone to cracking. It is also important that the finish have good scratch and mar resistance and be derived from compositions that are characterized by low levels of volatile organic chemicals such as solvents and the like. Finally, such a clearcoat should be capable of application over a variety of basecoats and have excellent adhesion.